Bilateral scapular kinematics, asymmetries and shoulder pain in wheelchair athletes

Background Shoulder pain is the most common complaint for wheelchair athletes. Scapular orientation and dyskinesia are thought to be associated with shoulder pathology, yet no previous studies have examined the bilateral scapula kinematics of wheelchair athletes during propulsion. Research question To examine bilateral scapular kinematics of highly trained wheelchair rugby (WR) players and any associations with self-reported shoulder pain during everyday wheelchair propulsion. Methods Ten WR players (5 with shoulder pain, 5 without) performed 2 × 3-minute bouts of exercise in their everyday wheelchair on a wheelchair ergometer at two sub-maximal speeds (3 and 6 km∙h-1). During the final minute, 3D kinematic data were collected at 100 Hz to describe scapulothoracic motion relative to each propulsion cycle. Instantaneous asymmetries in scapular orientation between dominant and non-dominant sides were also reported. Differences in scapular kinematics and propulsion asymmetries were compared across shoulders symptomatic and asymptomatic of pain. Results An internally rotated, upwardly rotated and anteriorly tilted scapula was common during wheelchair propulsion and asymmetries ≤ 14° did exist, yet minimal changes were observed across speeds. Participants with bilateral shoulder pain displayed a less upwardly rotated scapula during propulsion, however large inter-individual variability in scapular kinematics was noted. Significance Scapular asymmetries are exhibited by wheelchair athletes during wheelchair propulsion, yet these were not exacerbated by increased speed and had limited associations to shoulder pain. This suggests that propulsion kinematics of highly trained athletes may not be the primary cause of pain experienced by this population.